U.S. patent number 8,277,349 [Application Number 12/712,967] was granted by the patent office on 2012-10-02 for actuation system.
This patent grant is currently assigned to Exlar Corporation. Invention is credited to Timothy A. Erhart, James H. Sandlin, Terrence L. Thompson, William J. Zerull.
United States Patent |
8,277,349 |
Erhart , et al. |
October 2, 2012 |
**Please see images for:
( Certificate of Correction ) ** |
Actuation system
Abstract
An actuation system includes a prime mover, a mechanical option
module, an actuator, and a controller. The prime mover includes a
drive shaft. The mechanical option module includes a housing, an
input shaft coupled to the drive shaft, an output shaft, and a
planetary gear module. The planetary gear module includes a sun
gear coupled to the input shaft, a planet carrier coupled to the
output shaft, an outer ring, and planet gears meshed with the sun
gear and the outer ring. The application-specific module is
connected to the housing and configured to selectively influence
movement of the outer ring of the planetary gear module. The
actuator includes an actuator input shaft coupled to the output
shaft of the mechanical option module. The controller controls an
operation of at least one of the prime mover, the mechanical option
module, and the actuator.
Inventors: |
Erhart; Timothy A. (Chanhassen,
MN), Zerull; William J. (Minneapolis, MN), Thompson;
Terrence L. (Minneapolis, MN), Sandlin; James H.
(Shakopee, MN) |
Assignee: |
Exlar Corporation (Chanhassen,
MN)
|
Family
ID: |
42666213 |
Appl.
No.: |
12/712,967 |
Filed: |
February 25, 2010 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20110053723 A1 |
Mar 3, 2011 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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61155793 |
Feb 26, 2009 |
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61155418 |
Feb 25, 2009 |
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Current U.S.
Class: |
475/2; 475/3;
475/7 |
Current CPC
Class: |
F16H
3/72 (20130101); F16H 25/20 (20130101); F16H
2025/2087 (20130101); F16H 25/2204 (20130101); F16H
2025/209 (20130101) |
Current International
Class: |
F16H
3/72 (20060101) |
Field of
Search: |
;475/3,7,2 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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20012242 |
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Dec 2000 |
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DE |
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0454530 |
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Oct 1991 |
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EP |
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1500856 |
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Jan 2005 |
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EP |
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1174093 |
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Mar 1959 |
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FR |
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2116921 |
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Jul 1972 |
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FR |
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2216980 |
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Oct 1989 |
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GB |
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2004150620 |
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May 2004 |
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JP |
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Other References
International Search Report and Witten Opinion mailed Oct. 13,
2010. cited by other .
Exlar Corporation, Exlar 2008 Product Catalog, 2008, pp. 78, 95 and
106 (140 total pages). cited by other .
Exlar Corporation, Spring Return Assembly Extension, 2005, 3 pages.
cited by other .
McGraw Hill, "Marks Standard Handbook for Mechanical Engineers,"
Tenth Edition, 1996, pp. 11-8 to 11-9 (shown on 1 page). cited by
other .
Supplemental European Search Report for European Application No.
10746837.3, mailed Jul. 2, 2012, 7 pages. cited by other.
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Primary Examiner: Estremsky; Sherry
Attorney, Agent or Firm: Merchant & Gould P.C.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This Application claims priority to U.S. Provisional Application
No. 61/155,418 filed on Feb. 25, 2009, titled "UNIVERSAL ACTUATOR,"
and to U.S. Provisional Application No. 61/155,793 filed on Feb.
26, 2009, titled "UNIVERSAL ACTUATOR," the disclosures of which are
hereby incorporated by reference in their entireties.
Claims
What is claimed is:
1. An apparatus comprising: a housing; an input shaft arranged and
configured to receive a rotary input; an output shaft; a planetary
gear module including a sun gear coupled to the input shaft, a
planet carrier coupled to the output shaft, an outer ring, and
planet gears meshed with the sun gear and the outer ring, wherein
the outer ring is moveable relative to the housing; and an
application-specific module coupled to the housing and arranged and
configured to influence movement of the outer ring relative to the
housing, the application-specific module further comprising a brake
to selectively permit rotation of the outer ring of the planetary
gear module and to selectively inhibit rotation of the outer ring
of the planetary gear module, and further comprising an energy
storage device, wherein the application-specific module is arranged
and configured to deliver energy from the energy storage device
while the brake selectively permits rotation of the outer ring.
2. The apparatus of claim 1, wherein the application-specific
module is arranged and configured to selectively influence movement
of the outer ring relative to the housing.
3. The apparatus of claim 2, wherein the application-specific
module further comprises a secondary input shaft coupled to the
outer ring such that the outer ring rotates upon rotation of the
secondary input shaft.
4. The apparatus of claim 3, wherein the secondary input shaft is a
manual input shaft arranged and configured to receive a manual
rotary input.
5. The apparatus of claim 3, wherein the secondary input shaft is
connected to a secondary drive unit.
6. The apparatus of claim 5, wherein the secondary drive unit is
arranged and configured to provide a secondary rotary input to the
secondary input shaft upon failure of a prime mover to provide the
rotary input.
7. The apparatus of claim 5, wherein the secondary drive unit is
arranged and configured to provide a secondary rotary input at the
same time as a prime mover provides the rotary input.
8. The apparatus of claim 1, further comprising a bearing assembly
connected to the housing and supporting the planetary gear module,
while permitting rotation of the outer ring relative to the
housing.
9. The apparatus of claim 1, further comprising an actuator having
an actuator input shaft.
10. The apparatus of claim 9, wherein the actuator is a screw type
actuator.
11. The apparatus of claim 10, wherein the actuator is a linear
actuator further comprising: transmission rollers coupled to the
actuator input shaft; and an output rod coupled to the transmission
rollers, wherein the transmission rollers are arranged and
configured to translate the output rod along a linear axis upon
rotation of the actuator input shaft.
12. The apparatus of claim 9, wherein the actuator is a rotary
actuator.
13. An actuation system comprising: a prime mover having a drive
shaft; a mechanical option module including: a housing; an input
shaft coupled to the drive shaft; an output shaft; a planetary gear
module including a sun gear coupled to the input shaft, a planet
carrier coupled to the output shaft, an outer ring, and planet
gears meshed with the sun gear and the outer ring; and an
application-specific module connected to the housing and configured
to selectively influence rotation of the outer ring of the
planetary gear module, the application-specific module comprising a
brake to selectively permit rotation of the outer ring of the
planetary gear module and to selectively inhibit rotation of the
outer ring of the planetary gear module, and further comprising an
energy storage device, wherein the application-specific module is
arranged and configured to deliver energy from the energy storage
device while the brake selectively permits rotation of the outer
ring; an actuator having an actuator input shaft, the actuator
input shaft coupled to the output shaft of the mechanical option
module; and a controller that controls at least one of the prime
mover, the mechanical option module, and the actuator.
14. The actuation system of claim 13, wherein the controller
controls the application-specific module to selectively influence
rotation of the outer ring.
15. A method of generating an output: rotating a sun gear of a
planetary gear module upon receipt of a rotary input, the planetary
gear module including planet gears, a planet carrier, and an outer
ring; selectively influencing rotation of the outer ring of the
planetary gear module relative to a housing to adjust rotation of
an output shaft including: storing energy in an energy storage
device; and delivering the energy to the outer ring of the
planetary gear module upon an occurrence of an event to cause
rotation of the output shaft; and actuating a linear actuator with
the output shaft.
16. The method of claim 15, wherein the event is a loss of
electrical power to a prime mover providing the rotary input.
17. The method of claim 16, wherein delivering the energy to the
outer ring causes an output rod of the linear actuator to translate
to a predetermined position.
18. The method of claim 15, wherein selectively influencing
rotation of the outer ring further comprises: inhibiting rotation
of the outer ring; and releasing the outer ring to permit the outer
ring to rotate upon the occurrence of an event.
19. The method of claim 15, wherein selectively influencing
rotation of the outer ring comprises: receiving a manual rotary
input; and rotating the outer ring with the manual rotary
input.
20. The method of claim 15, wherein selectively influencing
rotation of the outer ring comprises: receiving a second rotary
input; and rotating the outer ring using the rotary input.
21. The method of claim 20, wherein rotating the outer ring using
the rotary input causes a speed of the output shaft to
increase.
22. The method of claim 20, wherein the second rotary input is a
redundant input that is provided when the rotary input is no longer
provided to the sun gear.
23. An apparatus comprising: a housing; an input shaft arranged and
configured to receive a rotary input; an output shaft; a planetary
gear module including a sun gear coupled to the input shaft, a
planet carrier coupled to the output shaft, an outer ring, and
planet gears meshed with the sun gear and the outer ring, wherein
the outer ring is moveable relative to the housing; an
application-specific module coupled to the housing and arranged and
configured to influence movement of the outer ring relative to the
housing; and a screw-type linear actuator having an actuator input
shaft coupled to the output shaft, the actuator further comprising:
transmission rollers coupled to the actuator input shaft; and an
output rod coupled to the transmission rollers, wherein the
transmission rollers are arranged and configured to translate the
output rod along a linear axis upon rotation of the actuator input
shaft.
24. The apparatus of claim 23, wherein the application-specific
module is arranged and configured to selectively influence movement
of the outer ring relative to the housing.
25. The apparatus of claim 24, wherein the application-specific
module further comprises a secondary input shaft coupled to the
outer ring such that the outer ring rotates upon rotation of the
secondary input shaft.
26. The apparatus of claim 25, wherein the secondary input shaft is
a manual input shaft arranged and configured to receive a manual
rotary input.
27. The apparatus of claim 25, wherein the secondary input shaft is
connected to a secondary drive unit.
28. The apparatus of claim 27, wherein the secondary drive unit is
arranged and configured to provide a secondary rotary input to the
secondary input shaft upon failure of a prime mover to provide the
rotary input.
29. The apparatus of claim 27, wherein the secondary drive unit is
arranged and configured to provide a secondary rotary input at the
same time as a prime mover provides the rotary input.
30. The apparatus of claim 23, further comprising a bearing
assembly connected to the housing and supporting the planetary gear
module, while permitting rotation of the outer ring relative to the
housing.
31. The apparatus of claim 23, wherein the application-specific
module further comprises a brake to selectively permit rotation of
the outer ring of the planetary gear module and to selectively
inhibit rotation of the outer ring of the planetary gear
module.
32. The apparatus of claim 23, wherein the actuator is a rotary
actuator.
33. The apparatus of claim 23, wherein the application-specific
module comprises a sensor coupled to the outer ring and to the
housing to detect a torque on the outer ring.
34. An actuation system comprising: a prime mover having a drive
shaft; a mechanical option module including: a housing; an input
shaft coupled to the drive shaft; an output shaft; a planetary gear
module including a sun gear coupled to the input shaft, a planet
carrier coupled to the output shaft, an outer ring, and planet
gears meshed with the sun gear and the outer ring; and an
application-specific module connected to the housing and configured
to selectively influence rotation of the outer ring of the
planetary gear module; a screw-type linear actuator having an
actuator input shaft, the actuator input shaft coupled to the
output shaft of the mechanical option module and further
comprising: transmission rollers coupled to the actuator input
shaft; and an output rod coupled to the transmission rollers,
wherein the transmission rollers are arranged and configured to
translate the output rod along a linear axis upon rotation of the
actuator input shaft; and a controller that controls at least one
of the prime mover, the mechanical option module, and the
actuator.
35. The actuation system of claim 34, wherein the controller
controls the application-specific module to selectively influence
rotation of the outer ring.
36. A method of generating an output: rotating a sun gear of a
planetary gear module upon receipt of a rotary input, the planetary
gear module including planet gears, a planet carrier, and an outer
ring; selectively influencing rotation of the outer ring of the
planetary gear module relative to a housing to adjust rotation of
an output shaft, including: receiving a manual rotary input; and
rotating the outer ring with the manual rotary input; and actuating
a linear actuator with the output shaft.
37. The method of claim 36, wherein selectively influencing
rotation of the outer ring further comprises: inhibiting rotation
of the outer ring; and releasing the outer ring to permit the outer
ring to rotate upon the occurrence of an event.
38. A method of generating an output: rotating a sun gear of a
planetary gear module upon receipt of a rotary input, the planetary
gear module including planet gears, a planet carrier, and an outer
ring; selectively influencing rotation of the outer ring of the
planetary gear module relative to a housing to adjust rotation of
an output shaft, including: receiving a second rotary input; and
rotating the outer ring using the second rotary input, wherein the
rotating of the outer ring using the second rotary input causes a
speed of an output shaft to increase; and actuating a linear
actuator with the output shaft.
39. A method of generating an output: rotating a sun gear of a
planetary gear module upon receipt of a rotary input, the planetary
gear module including planet gears, a planet carrier, and an outer
ring; selectively influencing rotation of the outer ring of the
planetary gear module relative to a housing to adjust rotation of
an output shaft, including: receiving a second rotary input;
rotating the outer ring using the second rotary input, wherein the
second rotary input is a redundant input that is provided when the
rotary input is no longer provided to the sun gear; and actuating a
linear actuator with the output shaft.
Description
TECHNICAL FIELD
The present disclosure generally relates to rotational motion or
alternatively translating rotational motion to linear motion and
systems therefore; more particularly relates to electrically
powered motors, gear motors and linear actuators; and more
particularly still to an actuation system including a mechanical
option module that provides application-specific functionality to a
rotary or linear actuator.
BACKGROUND
Rotary and linear actuators are used in a wide variety of
applications. A common configuration of a rotary actuator begins
with a motion controllable electric motor. A gear reducer is added
to the motor to increase torque output and improve system
stability. Another common design of an actuator (for linear output
motion) includes a motor, such as an electric motor that generates
rotational motion at its output shaft. A linear actuator converts
that motion into linear motion that is then applied to the system's
load. In this example, the output motion (linear) is applied such
that the load is moved along the same or similar path as the linear
actuator's output shaft.
Sometimes particular applications require additional functionality.
In order to provide this functionality, a customized design may be
required that is specifically tailored to the application. Such
custom designed actuators can be expensive, require considerable
design time, and add a significant amount of time to produce. In
some cases, there may not be a suitable design that provides the
functionality required by the application.
SUMMARY
In general terms, this disclosure is directed to an actuation
system including a planetary gear module. In one possible
configuration and by non-limiting example, an apparatus selectively
influences rotation of an outer ring of the planetary gear module
relative to a housing. In some embodiments, the apparatus includes
a linear or rotary actuator.
One aspect is an apparatus including a housing, an input shaft, an
output shaft, a planetary gear module, and an application-specific
module. The input shaft is arranged and configured to receive a
rotary input. The planetary gear module includes a sun gear coupled
to the input shaft, a planet carrier coupled to the output shaft,
an outer ring, and planet gears meshed with the sun gear and the
outer ring. The outer ring is moveable relative to the housing. The
application-specific module is coupled to the housing and arranged
and configured to influence movement of the outer ring relative to
the housing.
Another aspect is an actuation system including a prime mover, a
mechanical option module, an actuator, and a controller. The prime
mover includes a drive shaft. The mechanical option module
includes: a housing; an input shaft coupled to the drive shaft; an
output shaft; a planetary gear module including a sun gear coupled
to the input shaft, a planet carrier coupled to the output shaft,
an outer ring, and planet gears meshed with the sun gear and the
outer ring; and an application-specific module connected to the
housing and configured to selectively influence rotation of the
outer ring of the planetary gear module. The actuator includes an
actuator input shaft, the actuator input shaft being coupled to the
output shaft of the mechanical option module. The controller
controls at least one of the prime mover, the mechanical option
module, and the actuator.
Yet another aspect is a method of rotating a sun gear of a
planetary gear module upon receipt of a rotary input, the planetary
gear module including planet gears, a planet carrier, and an outer
ring; selectively influencing rotation of the outer ring of the
planetary gear module relative to a housing to adjust rotation of
an output shaft; and actuating a linear actuator with the output
shaft.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic block diagram of an example actuation system
according to the present disclosure.
FIG. 2 is a schematic block diagram of an example linear actuator
of the actuation system shown in FIG. 1.
FIG. 3 is a schematic side view of another example linear actuator
of the actuation system shown in FIG. 1.
FIG. 4 is a schematic block diagram and cross-sectional view of an
example mechanical option module of the actuation system shown in
FIG. 1.
FIG. 5 is another schematic block diagram and cross-sectional view
of the example mechanical option module shown in FIG. 4.
FIG. 6 is a schematic cross-sectional view of an example mechanical
option module.
FIG. 7 is another schematic cross-sectional view of the example
mechanical option module shown in FIG. 6.
FIG. 8 is a schematic cross-sectional view of another example
mechanical option module.
FIG. 9 is a schematic cross-sectional view of another example
mechanical option module.
FIG. 10 is a schematic cross-sectional view of an alternative
embodiment of the mechanical option module shown in FIG. 9.
FIG. 11 is a schematic cross-sectional view of another example
mechanical option module.
FIG. 12 is a schematic cross-sectional view of another example
mechanical option module.
FIG. 13 is a schematic cross-sectional view of another example
mechanical option module.
FIG. 14 is a schematic block diagram and cross-sectional view of
another example mechanical option module.
FIG. 15 is a schematic cross-sectional view of another example
mechanical option module.
FIG. 16 is a schematic cross-sectional view of another example
mechanical option module.
DETAILED DESCRIPTION
Various embodiments will be described in detail with reference to
the drawings, wherein like reference numerals represent like parts
and assemblies throughout the several views. Reference to various
embodiments does not limit the scope of the claims attached hereto.
Additionally, any examples set forth in this specification are not
intended to be limiting and merely set forth some of the many
possible embodiments for the appended claims.
FIG. 1 is a schematic block diagram of an example actuation system
100. Actuation system 100 includes prime mover 102, mechanical
option module 104, rotational or linear actuator 106, and
controller 108. In one example, actuation system 100 operates to
generate a rotational motion (R1) using one or more prime movers
102. The rotational motion (R1) through mechanical option module
104 is converted into a linear motion (L1) via linear actuator 106.
The linear motion is applied by the linear actuator 106 to a load
110 to move it as desired. In another possible embodiment,
actuation system 100 converts the rotational motion (R1) into
another rotational motion (R2) through mechanical option module 104
and a rotary actuator 106.
Prime mover 102 is typically an engine or motor that delivers a
rotational force to an output shaft. Examples of prime movers 102
include electric motors (including AC and DC motors), a combustion
engine, a steam engine, a pneumatic motor, a hydraulic motor, or
any other device that generates rotational motion. In some
embodiments, two or more prime movers 102 are used. Further, in
some embodiments a motion may be applied manually in addition to
the motion generated by the prime mover.
Mechanical option module 104 represents the various modules that
can be arranged between prime mover 102 and the linear or rotary
actuator 106. Various mechanical option modules 104 are available
for performing a variety of functions, as described herein,
depending on the needs of a particular application. Mechanical
option module 104 receives the rotational motion generated by prime
mover 102. The motion is then transferred through the mechanical
option module 104 and delivered to the linear actuator 106. In some
embodiments, mechanical option module 104 operates to transform the
motion between prime mover 102 and linear actuator 106. For
example, in some embodiments the mechanical option module 104
operates to reduce the speed of rotation but increases the torque.
Other embodiments of mechanical option module 104 are used to
provide additional features or functionality. The use of a
mechanical option module allows the linear actuator to be used in a
variety of applications without requiring that a customized
actuator be designed and built to perform the necessary functions.
This reduces cost and time required for development and
delivery.
In some embodiments actuation system 100 includes a rotary or
linear actuator 106. A linear actuator 106 is a device that
converts rotary (input) motion (R1) into linear or axial motion
(L1). Examples of linear actuators 106 are shown in FIGS. 2-3.
Other embodiments include rotary actuators, such as a rotary
actuator that converts rotary motion (R1) into a different rotary
motion (R2). In some embodiments the mechanical option module 104
is coupled to the rotary output of the prime mover 102 and the
rotary input of the rotary or linear actuator 106. Another example
of a linear actuator 106 (106b) is an inverted roller screw
actuator, such as illustrated in FIG. 3.
Controller 108 controls the operation of actuation system 100. In
some embodiments, controller 108 is a computer. In other
embodiments, controller 108 includes a processing device, memory,
and interface components (such as input/output ports or other
communication ports). Examples of processing devices include a
microprocessor, a central processing unit, a microcontroller, a
programmable logic device, a field programmable gate array, and a
digital signal processing device. Other processing devices are used
in other embodiments. Processing devices can be of any general
variety such as a reduced instruction set computing (RISC) device,
a complex instruction set computing device (CISC), a minimal
instruction set computing device (MISC), or a specially designed
processing device such as an application-specific integrated
circuit (ASIC) device. Controller 108 is operable to control the
operation of any one of prime mover 102, mechanical option module
104, and rotary or linear actuator 106. In addition, in some
embodiments controller 108 receives feedback from load 110 (such as
from sensors or other communication devices not shown). Such
feedback can be used by controller 108 to adjust the operation of
actuation system 100 accordingly. In some embodiments, controller
108 is a single device, while in other embodiments controller
includes more than one device. Controller 108 is configured to
interact with any one or more of prime mover 102, mechanical option
module 104, and rotary or linear actuator 106 in the various
possible embodiments. In some embodiments controller 108 is
integrated with one or more of prime mover 102, mechanical option
module 104, and rotary or linear actuator 106. In another possible
embodiment, controller 108 is a switch. Some embodiments do not
include controller 108.
Some embodiments of controller 108 include computer readable
storage media. Examples of computer readable storage media include
a hard disk drive, a magnetic cassette, a flash memory card, a
digital video disk, a Bernoulli cartridge, a compact disc read only
memory, a digital versatile disk read only memory, random access
memory, read only memory, or other memory devices. In some
embodiments, computer readable storage media stores data
instructions that, when executed by a processing device, cause the
processing device to perform one or more of the methods,
operations, or functions described herein. In some embodiments,
computer readable storage media includes computer non-transitory
media. Yet other embodiments include computer readable media, which
may include forms of transitory and/or communication media.
As illustrated in FIG. 1, some embodiments of actuation system 100
are designed based on the principle of modularity. In other words,
in some embodiments certain components or modules of actuation
system 100 are interchangeable with other components or modules.
For example, in some embodiments the mechanical option module 104
is interchangeable with other mechanical option modules that
provide different features or functionality. In some embodiments
the modularity of the actuation system 100 provides for efficient
manufacturing and assembly of products to meet the particular needs
of a specific application.
In some embodiments, components or modules of actuation system 100
are designed for different levels of force or torque different
levels of travel life at a specified torque or force (e.g., several
grades of performance). Typically, components or modules that are
designed for lower performance can be manufactured more
inexpensively than those with higher performance requirements. As a
result, providing components or modules designed for various grades
of performance allows the least expensive module to be selected
that will meet the requirements of a specific application.
FIG. 2 is a schematic block diagram of an example linear actuator
106a. In this example, linear actuator 106a includes a housing 201,
screw mechanism 203, follower 205, and tube mechanism 207.
In some embodiments, linear actuator 106a is a screw type actuator
utilizing a screw mechanism 203 (such as a ball screw, acme screw,
or roller screw) mounted inside of housing 201. A periscoping tube
mechanism 207 provides the output force. One embodiment including
one or more transmission devices, a follower 205 is attached to the
moveable tube mechanism 207 inside the actuator housing 201 thereby
extending the tube mechanism 207 as the shaft of the screw
mechanism 203 rotates. The tube mechanism 207 is typically
supported and guided by a bearing at the front end of the actuator
housing.
Additional examples of linear actuators are described in U.S. Pat.
No. 5,491,372, titled "Electric Linear Actuator With Planetary
Action," and in U.S. Pat. No. 5,557,154, titled, "Linear Actuator
With Feedback Position Sensor Device."
FIG. 3 is a schematic side view of another example linear actuator
106b, with portions of linear actuator 106b being removed to show
internal components. Linear actuator 106b includes input shaft 302,
transmission rollers 304, output rod 306, and housing 308. When a
rotational force (R1) is provided to input shaft 302, output rod
306 is moved forward or backward between extended and retracted
positions in the directions L1.
Input shaft 302 is typically a single elongated and generally
cylindrical shaft. Input shaft 302 includes a first end 312 and a
second end 314. First end 312 is configured to receive a rotational
force, such as from mechanical option module 104 (shown in FIG. 1).
In some embodiments a shaft coupler (not shown) connects mechanical
option module 104 to first end 312. The rotational force is
transferred through input shaft 302 to second end 314. Second end
314 of input shaft 302 is coupled to a transmission device, such as
transmission rollers 304, such that as the input shaft 302 rotates,
transmission rollers revolve around second end 314 of input shaft
302.
Transmission rollers 304 include a plurality of individual rollers
spaced around and coupled to the second end 314 of input shaft 302.
Rollers 304 include raised ribs 320 arranged in a generally helical
pattern that extend along the outer surface of rollers 304. Ribs
320 engage both the threaded second end 314 of input shaft 302 and
a threaded interior surface of output rod 306.
Output rod 306 typically includes an at least partially hollow
cylinder having an inner surface 322 and an outer surface 324. In
some embodiments inner surface 322 is threaded with helical ribs,
illustrated schematically at 324. The threaded helical ribs of
inner surface 322 engage with ribs320 of transmission rollers 304.
When transmission rollers 304 are caused to rotate by input shaft
302, ribs 320 of transmission rollers 304 engage with ribs or
threaded inner surface 322 causing translation of output rod 306 in
the forward of backward direction L1.
Examples of linear actuator 106b and other linear actuators are
described in more detail in U.S. Publication No. 2007/0137329 (U.S.
Ser. No. 11/259,175), titled "Method and Apparatus for an Inverted
Roller Screw."
Mechanical option module 104 will now be described in more detail
below with reference to FIGS. 4-16. A block diagram illustrating a
first exemplary configuration of a mechanical option module 104 is
shown in FIG. 4, followed by a variety of additional examples shown
in FIGS. 5-13, all of which utilize the first configuration of the
mechanical option module 104 or variations thereof. A block diagram
illustrating a second exemplary configuration of a mechanical
option module 104 is shown in FIG. 14, followed by a variety of
additional examples shown in FIGS. 15-16 that utilize the second
exemplary configuration of the mechanical option module 104.
FIGS. 4 and 5 illustrate an example of mechanical option module
104. FIG. 4 is a schematic block diagram and cross-sectional view
of an example mechanical option module 104. FIG. 5 is another
schematic block and cross-sectional view of the example mechanical
option module 104. The cross-section shown in FIG. 5 is through
line A-A, illustrated in FIG. 4. In some embodiments, mechanical
option module 104 includes input shaft 402, output shaft 404,
planetary gear module 406, bearing assembly 408, an
application-specific module 410, and housing 450. Mechanical option
module 104 includes one of a variety of selectable
application-specific modules 410 that can be selected to provide
various features and functionality appropriate for a particular
application. Regardless of the application-specific module
selected, mechanical option module 104 is configured to be coupled
to linear or rotary actuator 106 without requiring modification to
the actuator 106.
Mechanical option module 104 receives a rotational input at input
shaft 402. In some embodiments a shaft coupler is used to connect
input shaft 402 to another device (e.g., to an output shaft of
prime mover 102). Mechanical option module 104 also includes an
output shaft 404 where a rotational output is provided to another
device (e.g., to an input shaft of linear actuator 106).
Planetary gear module 406 is included in some embodiments of
mechanical option module 104. Planetary gear module 406 typically
includes a sun gear 412, planet gears 414, planet carrier 416, and
outer ring 418. Bearings 420 and 422 are also included in some
embodiments. Planetary gear module 406 is rotatably supported by
bearings 442 and 444 and is coupled to housing 450 only through
application-specific module 410 in some embodiments.
In this example, sun gear 412 is formed at an end of input shaft
402. Sun gear 412 is typically a cylindrical gear including a
plurality of radially extending teeth. As input shaft 402 is caused
to rotate (e.g., by prime mover 102), the teeth of sun gear 412
also rotate. Sun gear 412 is sized to fit between planet gears
414.
A plurality of planet gears 414 are arranged around sun gear 412.
Planet gears 414 are typically cylindrical gears including a
plurality of radially extending teeth. Another embodiment includes
a helical tooth pattern. Teeth of planet gears are sized and
arranged to mate with teeth of sun gear 412 as well as an inner
surface of outer ring 418. In some embodiments planet gears 414
have a smaller diameter than sun gear 412. In some embodiments
planetary gear module includes at least three planet gears 414.
Additional planet gears 414 can be included in other embodiments up
to the maximum number that can physically fit within the space
available between the sun gear 412 and outer ring 418. Normally
three gears will be adequate. Other embodiments include other
quantities of planet gears 414. Planet gears are preferably
confined to a space between sun gear 412 and outer ring 418.
When sun gear 412 rotates, teeth of sun gear 412 transfer a torque
into planet gears 414. This force causes planet gears to rotate and
also to revolve around sun gear 412. When outer ring 418 is held
stationary, the rate of revolution of planet gears 414 is a
function of the rotational speed of sun gear and also a function of
the relative circumferences of sun gear 412 and planet gears 414
(or, stated another way, a function of the number of teeth of sun
gear 412 relative to planet gears 414).
Planet gears 414 are coupled at an end to planet carrier 416.
Planet gears 414 are free to rotate relative to planet carrier 416.
As planet gears 414 revolve around sun gear 412, force is
transferred into planet carrier 416 causing planet carrier 416 to
rotate. As a result, the rate of revolution of planet gears 414 is
equal to the rate of rotation of planet carrier 416. Planet carrier
416 is coupled or rigidly connected to output shaft 404.
Planetary gear module 406 provides an overall gear reduction from
input shaft 402 to output shaft 404. The gear reduction of one
stage is typically in a range from about three to about 10. Other
embodiments include cascading stages by connecting the output of
one stage to the input of the next stage. Cascading stages are used
to multiply these ratios accordingly (i.e. providing a gear
reduction in a range from about nine to about 100 with two stages).
In some embodiments that utilize multiple stage reduction, one
common outer ring 418 can be used having adequate length to
accommodate multiple stages of gear reduction with additional sun
gears 412, planet gears 414, planet carriers 416, and output shafts
404. When the outer ring 418 is fixed, the gear reduction causes
the speed of rotation of the input shaft to be greater than the
resulting speed of rotation of the output shaft. On the other hand,
the torque on the output shaft is greater than the torque at the
input shaft by the gear reduction ratio.
Outer ring 418 is the outer portion of planetary gear module 406.
In some embodiments, outer ring 418 includes an inner surface 432
and an outer surface 434. Inner surface 432 is typically a
cylindrical bore and includes a plurality of teeth (schematically
illustrated in FIG. 4 at 433). Inner surface 432 engages and meshes
with planet gears 414 as they revolve around sun gear 412. In some
embodiments outer surface 434 also includes a cylindrical bore and
may include a plurality of teeth along at least a portion of outer
surface 434. In some embodiments outer surface 434 is cylindrical,
but in other embodiments outer surface 434 includes a
non-cylindrical shape (such as including a radially extending gear
portion).
Bearings 420 and 422 are provided in some embodiments to separate
moving components from each other with low friction, while
providing support to components of the planetary gear module 406.
In one embodiment, bearings 420 and 422 are circular ball bearings.
Other example of bearings include needle bearings, bushings (e.g.,
bushings of bronze, sintered metals, plastics, or other materials,
such as those used in sleeve type bushings), and fluid bearings.
Bearing 420 supports input shaft 402 and locates sun gear 412 in
the center of planet gears 414 relative to outer ring 418. Bearing
422 separates planet carrier 416 from outer ring 418. Bearing 420
supports input shaft 402 and bearing 422 supports output shaft 404,
providing added strength and stability.
Mechanical option module 104 also includes bearing assembly 408. In
this example, bearing assembly 408 includes bearings 442 and 444.
Bearing assembly 408 is connected at one edge to outer surface 434
of outer ring 418 and at another edge to a portion of
application-specific module 410. Bearing assembly 408 operates to
allow outer ring 418 of planetary gear module 406 to rotate
independent of (or not as determined by) application-specific
module 410. Bearing assembly 408 is just one example of a variety
of possible embodiments that can utilize different bearing
assemblies or different supporting structures other than bearings.
Other embodiments utilize other structures that permit outer ring
418 to rotate independent of housing 450.
Application-specific module 410 is one of a variety of possible
modules that is selected to provide one or more features (and/or to
perform one or more functions) that are desired for a particular
application. Application-specific module 410 is connected to
housing 450. Application-specific module 410 is also arranged and
configured to connect with bearing assembly 408 and to interface
with outer surface 434. Examples of application-specific modules
410 are described in more detail with reference to FIGS. 6-12
below.
FIGS. 6 and 7 illustrate an example of a first embodiment of a
mechanical option module 104. FIG. 6 is a schematic cross-sectional
view of the first embodiment of the mechanical option module 104.
FIG. 7 is another schematic cross-sectional view of the first
embodiment of the mechanical option module 104. In this embodiment,
application-specific module 410 includes a manual drive feature.
The manual drive feature is useful, for example, as a backup in the
event that power is lost. In this event, the manual drive can be
used to manually operate the actuation system.
Mechanical option module 104 includes input shaft 402, output shaft
404, planetary gear module 406, bearing assembly 408 (including
bearings 420 and 422), application-specific module 410, and housing
450. Planetary gear module 406 includes an outer ring 418 having an
outer surface 434.
In some embodiments, outer ring 418 has an outer surface 434 having
first region 602, a second region 604 (also referred to herein as a
protruding gear region), and a third region 606. First and third
regions 602 and 606 are generally parallel with each other around a
circumference of outer ring 418. In some embodiments first and
third regions 602 and 606 are substantially smooth. Second region
604 protrudes radially from first and third regions 602 and 606,
and preferably includes a plurality of radially extending teeth. In
some embodiments protruding gear region 604 includes a helical gear
pattern. This protruding gear region 604 is not included in all
embodiments.
In this embodiment, application-specific module 410 includes a
manual drive assembly 612 that prevents outer ring 418 from
rotating due to input torque at input shaft 402. One example of a
manual drive assembly 612 is a worm screw 614. Worm screw 614
preferably includes a shaft 616, a helical protrusion 618, and a
manual input port 620. Additional support members are included in
some embodiments to support worm screw 614, such as to connect and
support manual drive assembly to housing 450.
Input port 620 is arranged at an end of shaft 616 and is arranged
and configured to receive an input, such as a manual input at input
port 620. In one example, input port 620 has a hex cross-section
and is sized to be engaged by a socket wrench. Other embodiments
include other configurations, such as having a square or slotted
head. Another possible embodiment includes a knob or handle sized
and configured to be grasped and rotated or otherwise moved by a
human hand. An input supplied to input port 620 causes shaft 616 to
rotate.
When shaft 616 rotates, the helical protrusion 618 also rotates.
Helical protrusion is arranged to mate with teeth of protruding
gear region 604. The rotation of helical protrusion 618 causes
rotation of outer ring 418 of planetary gear module 406. The
rotation of outer ring 418 can be reversed by rotating shaft 616 in
an opposite direction. The manual input is transferred through
planetary gear module 406 and to output shaft 404, so as to operate
the actuator (e.g., rotary or linear actuator 106, shown in FIG. 1
and sometimes referred to hereafter as actuator 106 for
convenience).
During normal operation, a manual input is not provided to input
port 620. In some embodiments, manual drive assembly 612 operates
as a brake when not providing an input to prevent outer ring 418 of
planetary gear module 406 from rotating relative to
application-specific module 410 and housing 450. Any force applied
to outer ring 418 (such as from prime mover 102, shown in FIG. 1)
is hindered by the presence of the stationary helical protrusion
618. If necessary, a lock or brake is included in some embodiments
to prevent unintentional rotation of manual drive assembly 612.
During manual operation, an input is supplied to input port 620. In
order to prevent input shaft 402 from rotating during the manual
operation, prime mover 102 includes a brake in some embodiments or
a separate brake is included in mechanical option module 104 to
prevent or inhibit rotation of input shaft 402.
FIG. 8 is a schematic cross-sectional view of a second embodiment
of a mechanical option module 104. Mechanical option module 104
includes input shaft 402, output shaft 404, planetary gear module
406, bearing assembly 408 (including bearings 420 and 422),
application-specific module 410, and housing 450. Planetary gear
module 406 includes an outer ring 418 having an outer surface 434.
In this embodiment, application-specific module 410 allows
mechanical option module 104 to include a second drive unit, such
as a secondary motor.
In some embodiments, outer ring 418 includes protruding gear
section 604 (as discussed in more detail herein with respect to
FIGS. 6 and 7) having a plurality of radially extending teeth.
Protruding gear section 604 is a spur gear in some embodiments.
In this embodiment, application-specific module 410 is arranged and
configured to receive power from a secondary motor 802. The
secondary motor includes an output shaft 804 (alternatively, output
shaft 804 is coupled to the rotor of motor 802, such as using a
shaft coupler). A gear 806 is connected to output shaft 804 so as
to rotate at the same rate as output shaft 804. Gear 806 is
arranged so as to mesh with teeth of protruding gear region 604 of
outer ring 418, to transfer rotational power into outer ring 418
when power is supplied by secondary motor 802. Power transferred to
outer ring 418 passes through planetary gear module 406 and is
output at output shaft 404.
An example of secondary motor 802 is a servo motor, but other
embodiments include other drive units. Secondary motor 802
preferably includes an integrated brake to prevent gear 806 from
unintentional rotation. When secondary motor 802 is not supplying
power to gear 806, the brake is engaged. The brake is disengaged
when secondary motor 802 is supplying power to gear 806.
In this embodiment, mechanical option module 104 allows two motors
(or other drive units) to be used to control the operation of the
planetary gear module, and accordingly the operation of the
actuator via the resulting motion at output shaft 404 (e.g.,
actuator 106, shown in FIG. 1). In some embodiments, for example,
the prime mover (e.g., prime mover 102, shown in FIG. 1) is a high
speed motor with relatively low torque, while the secondary motor
802 is a low speed motor with relatively high torque. The opposite
arrangement is used in other embodiments.
In yet other embodiments prime mover 102 and secondary motor 802
are the same or similar drive units. For example, in some
embodiments secondary motor 802 is a redundant motor configured to
be activated when controller 108 detects a failure of the prime
mover.
Prime mover 102 and secondary motor 802 can be operated at the same
time, or can be operated individually or selectively.
Although this example of a second embodiments of mechanical option
module 104 transfers power between secondary motor 802 and outer
ring 418 through the use of spur gears, other embodiments include
other power transfer mechanisms. For example, some embodiments
include a belt or chain to transfer power from secondary motor 802
to outer ring 418.
FIG. 9 is a schematic cross-sectional view of a third embodiment of
a mechanical option module 104. Mechanical option module 104
includes input shaft 402, output shaft 404, planetary gear module
406, bearing assembly 408 (including bearings 420 and 422), and
application-specific module 410. Planetary gear module 406 includes
an outer ring 418 having an outer surface 434 (including a
protruding gear region 604). In this embodiment,
application-specific module 410 allows mechanical option module 104
to selectively disengage the actuator 106. In this way, the linear
actuator becomes freely (or substantially freely) movable, such as
during an emergency or power failure situation.
In this embodiment, application-specific module 410 includes
holding brake 902. Holding brake 902 is arranged and configured to
apply a braking force to protruding gear region 604. In one
example, during normal operation the holding brake 902 operates to
prevent outer ring 418 from rotating by applying a braking force to
protruding gear region 604. The holding brake 902 can also be
disengaged, so as to release the braking force. When disengaged,
holding brake 902 allows outer ring 418 to freely rotate. As a
result, output shaft 404 is free to rotate independent of input
shaft 402. In some embodiments when the output shaft 404 is freely
rotatable the mechanical option module is referred to as having a
floating output rod.
This embodiment is useful in many applications. For example, in one
embodiment an actuation system (e.g., 100, shown in FIG. 1,
including a prime mover 102, mechanical option module 104, and
actuator 106) is part of a power steering system, such as to move a
rudder of a ship. In the event that power is lost to the prime
mover 102, it is desirable to continue operating the rudder
manually so that the ship can be steered. When power is lost,
holding brake 902 is released (either automatically upon the loss
of power, or manually) to allow the rudder to be manually steered
without the assistance of the prime mover. Because outer ring 418
is free to rotate, the mechanical option module does not oppose, or
substantially oppose, rotation at output shaft 404. Thus, actuator
106 is also free to move with the movement of the rudder. In some
embodiments an actuator 106 is used that is highly efficient, such
as having a high lead.
In another possible embodiment, holding brake 902 is normally
disengaged, allowing outer ring 418 to freely rotate. Upon the
occurrence of an event, such as a loss of power, holding brake 902
is automatically engaged, thereby preventing (or reducing) rotation
of outer ring 418.
These examples are provided to illustrate only several possible
applications of the third embodiment of the mechanical option
module. Other embodiments are used in a variety of other
applications.
FIG. 10 is a schematic cross-sectional view of an alternative
embodiment of the mechanical option module shown in FIG. 9. In this
example, mechanical option module 104 includes input shaft 402,
output shaft 404, planetary gear module 406, bearing assembly 408
(including bearings 420 and 422), and application-specific module
410. Planetary gear module 406 includes an outer ring 418 having an
extended brake portion 1000. The extended brake portion includes
braking surface 1002. Application-specific module 410 also includes
holding brake 1004.
In this example, outer ring 418 does not include a protruding brake
portion. Rather, outer ring 418 includes an extended brake portion
1000 rigidly connected thereto. Brake 1004 is arranged around a
braking surface 1002 of extended brake portion 1000. When brake
1000 is engaged, a holding force is applied to braking surface 1002
to prevent or reduce rotation of outer ring 418 with respect to
housing 450. When brake 1000 is not engaged, extended braking
portion 1000 and outer ring 418 are free to rotate relative to
housing 450 due to torques that may be applied to input or output
shafts 402 and 404.
FIG. 11 is a cross-sectional view of a fourth embodiment of a
mechanical option module 104. Mechanical option module 104 includes
input shaft 402, output shaft 404, planetary gear module 406,
bearing assembly 408 (including bearings 420 and 422),
application-specific module 410, and housing 450. Planetary gear
module 406 includes an outer ring 418 having an outer surface
434.
In this embodiment, application-specific module 410 includes an
internal spring return. For example, in some situations it is
desirable to automatically return a linear actuator to one end or
the other of its permissible stroke upon the receipt of a signal or
upon the loss or power. The internal spring return is operable in
some embodiments to return the linear actuator to a predetermined
position even in a situation where power has been lost. Other
embodiments include other storage devices than a spring, such as a
pneumatic cylinder, a hydraulic cylinder, or other energy storage
devices.
In this embodiment, application-specific module 410 includes
holding brake 902 and spring 1102. In some embodiments holding
brake 902 is the same as described herein with reference to FIG.
9.
Spring 1102 is a device suitable for storing power and then
selectively releasing the power to cause outer ring 418 to rotate.
In the illustrated example, spring 1102 is a flat spiral spring
(also known as a clock spring). The centermost end 1104 of the flat
spiral spring 1102 is coupled to outer surface 434 of outer ring
418. The outermost end 1106 of the flat spiral spring 1102 is
coupled to housing 450 (or another portion of application-specific
module 410 that is itself coupled to housing 450). Other
embodiments include other springs. For example, another possible
embodiment includes a helical torsion spring (not shown in FIG. 11)
arranged around outer ring 418 and sharing a common central axis.
One end of the helical spring is coupled to housing 450, and the
other end of the helical spring is coupled to outer ring 418 (such
as to a side of protruding gear region 604). Other springs or
energy storage devices are used in other embodiments.
During normal operation the holding brake 902 operates to inhibit
rotation of outer ring 418. Spring 1102 is pre-wound to store
energy therein. Normal operation of actuator 106 does not require
energy to work against the spring 1102. Brake 902 holds the spring
energy and actuator operation occurs with prime mover 102 supplying
rotational torque to input shaft 402 and to actuator 106 via output
shaft 404. Holding brake 902 can be selectively disengaged to
release outer ring 418, such as upon the loss of power to holding
brake 902 or upon receipt of a signal from a controller (e.g., 108,
shown in FIG. 1). When holding brake 902 is released, the energy
stored in spring 1102 is supplied to outer ring 418 to cause output
shaft 404 to rotate (either clockwise or counterclockwise,
depending on the orientation of spring 1102). The rotation of
output shaft 404 is supplied to actuator 106 to move the output rod
or shaft to a desired position.
In some embodiments the prime mover is capable of backdriving. As a
result, some embodiments include an additional brake coupled to the
prime mover or input shaft 402 to prevent backdriving when power is
supplied from the spring 1102.
FIG. 12 is a schematic cross-sectional view of a fifth embodiment
of a mechanical option module 104. Mechanical option module 104
includes input shaft 402, output shaft 404, planetary gear module
406, bearing assembly 408 (including bearings 420 and 422),
application-specific module 410, and housing 450. Housing 450
includes a spring return region 1220 having a first end 1222 and a
second end 1224. Planetary gear module 406 includes an outer ring
418 having an outer surface 434. Similar to the embodiment
described with reference to FIG. 11, this alternate embodiment also
provides an internal spring return capability. This embodiment is
similar to that of FIG. 11, except that a linear spring is utilized
to store the energy in place of a torsional spring.
In this embodiment, application-specific module 410 includes spur
gear 1202, lead screw 1204, spring 1206, nut 1208, and brake 1210.
Spur gear 1202 includes a plurality of radially extending teeth
that intermesh with teeth of protruding gear region 604 of outer
ring 418. Lead screw 1204 is coupled to spur gear 1202 and shares a
common axis of rotation with spur gear 1202. Lead screw 1204
includes a helix angle suitable to allow the screw to backdrive. In
some embodiments the helix angle is in a range from about 20
degrees to about 45 degrees or more. Other embodiments include
other helix angles. Lead screw 1204 extends into spring return
region 1220, through second end 1224, and to first end 1222. In
some embodiments lead screw 1204 is supported relative to spring
return region 1220 with one or more ball bearings.
Spring 1206 is contained within spring return region 1220. In this
example, spring 1206 is a helical compression spring. Lead screw
1204 extends approximately along a central axis of spring 1206. One
end of helix compression spring 1206 is connected to or presses
against first end 1222 of spring return region 1220. The other end
of spring 1206 is connected to or presses against nut 1208.
Nut 1208 is a threaded nut that rides on lead screw 1204 in the
region between first and second ends 1222 and 1224 of spring return
region 1220. Nut 1208 includes a threaded inner surface that causes
nut 1208 to translate between first and second ends 1222 and 1224
as lead screw 1204 rotates. In some embodiments nut 1208 includes
arms that ride within tracks (not shown) formed in sidewalls of
spring return region 1220, which prevent nut 1208 from rotating
with the rotation of lead screw 1204.
Brake 1210 is provided to selectively engage spur gear 1202, or
alternatively, protruding gear region 604. When engaged, brake 1210
prevents rotation of the respective gear 1202 or gear region 604,
which also prevents rotation of outer ring 418 of planetary gear
module 406. In addition, brake 1210 is operable to prevent energy
transfer between spring 1206 and planetary gear module 406 when it
is engaged. When disengaged, brake 1210 allows rotation of gear
1202, gear region 604, and outer ring 418. Brake 1210 also allows
energy transfer between spring 1206 and planetary gear module 406
when it is disengaged.
One possible method of operating a mechanical option module 104,
such as the embodiment shown in FIG. 12 is as follows. It will be
appreciated by those of skill in the art that while the example
described herein refers to a linear actuator 106, that this
embodiment could also be employed in an environment in which the
rotary actuator 106 is present. The mechanical option module 104 is
operated so that in the event that power is lost (or upon the
occurrence of another event), the mechanical option module 104 will
supply a rotational force at output shaft 404 sufficient to cause
an attached output rod of a linear actuator 106 to advance to a
desired position (typically, either the fully extended or fully
retracted position). The mechanical option module can be operated
to supply this force without electrical power present (e.g., in the
absence of electrical power). At least some of the other mechanical
option modules discussed herein can be similarly operated.
The mechanical option module is first operated so as to store
energy in spring 1206. To do so, brake 1210 is disengaged and a
rotational force is received from a prime mover (e.g., prime mover
102, shown in FIG. 1). The direction of rotation is selected so as
to advance an output rod of the linear actuator (e.g., linear
actuator 106), coupled to output shaft 404, to the position to
which the output rod is intended to move upon loss of power (or
occurrence of another event, such as receipt of a signal from
controller 108, shown in FIG. 1).
Once the linear actuator has reached the desired position, movement
of the output rod ceases (e.g., due to having reached a physical
limit of the linear actuator or due to the engagement of a brake or
other selective stopping mechanism). When this limit is reached,
the prime mover continues supplying power to input shaft 402. The
power is transferred through planetary gear module 406. Because
output shaft 404 is now prevented from further rotation by the
linear actuator, outer ring 418 begins to rotate. As outer ring 418
rotates, spur gear 1202 also rotates, thereby causing rotation of
lead screw 1204. As the lead screw rotates, nut 1208 is forced in
the direction of first end 1222 of spring return region 1220,
compressing spring 1206. As spring 1206 is compressed, energy is
stored within the spring 1206.
Once sufficient energy has been stored in spring 1206, brake 1210
is engaged and the prime mover stops. There are multiple methods of
determining when sufficient energy has been stored in spring 1206.
In some embodiments, controller 108 (shown in FIG. 1) is programmed
to control the prime mover 102 (shown in FIG. 1) to compress spring
1206 a predetermined amount (such as by rotating input shaft 402 a
predetermined number of times after the output rod of the linear
actuator has reached the desired position). In another embodiment,
a pressure switch or motor current setting is used to determine
when sufficient energy has been stored. In yet another embodiment,
a limit sensor or force sensor is provided on the outer ring 418 to
determine when sufficient energy has been stored. The amount of
energy stored is sufficient to advance the output rod of the linear
actuator to the desired position (e.g., the fully extended
position) even if the output rod is at a position (e.g., the fully
retracted position) most distant from the desired position.
Once brake 1210 has been engaged, the linear actuator can be freely
operated. Spring 1206 is prevented from releasing the energy stored
therein by brake 1210, until the brake 1210 is disengaged, such as
by a controller, upon power loss, or by an operator. Brake 1210
avoids requiring prime mover 102 to continually work to maintain
spring 1206 in the compressed state during normal operation.
Accordingly, in some embodiments energy consumed by the prime mover
102 is reduced by utilizing brake 1210 during normal operation. In
some embodiments heat generated by prime mover 102 is also reduced.
Brake 1210 can be normally open or normally closed depending on the
desired operation. For example, a normally open brake 1210 can be
used so that spring 1206 is released upon a loss of power to brake
1210.
If power is lost or upon the occurrence of another event, brake
1210 is released (either automatically or manually). When brake
1210 is released, spring 1206 supplies energy to nut 1208. A
threaded inner surface of nut 1208 engages with the threaded lead
screw 1204 causing lead screw 1204 to backdrive. The rotation of
lead screw 1204 causes spur gear 1202 to rotate, and this force is
transferred into outer ring 418. As outer ring 418 rotates, output
shaft 404 is also caused to rotate so as to advance output rod of
the coupled linear actuator to the desired position. In some
embodiments the prime mover is capable of backdriving. As a result,
some embodiments include an additional brake coupled to the prime
mover or input shaft 402 to prevent backdriving when power is
supplied from the spring 1206.
Other embodiments include other or additional energy storage
devices than spring 1206. Examples of other energy storage devices
include other forms of springs, pneumatic or hydraulic
accumulators, and other energy storage devices. Multiple energy
storage devices are used in some embodiments.
FIG. 13 is a schematic cross-sectional view of a sixth embodiment
of a mechanical option module 104. Mechanical option module 104
includes input shaft 402, output shaft 404, planetary gear module
406, bearing assembly 408, application-specific module 410, and
housing 450. In this embodiment, application-specific module 410
includes one or more sensors to monitor the torque on mechanical
option module 104 and/or an attached actuator 106.
In one example, mechanical option module 104 includes torque sensor
1302. Torque sensor 1302 is connected at one end to outer surface
434 of outer ring 418. The other end of torque sensor 1302 is
connected to housing 450 (or another feature that is connected to
housing 450). Torque sensor 1302 may be in the form of strain gauge
elements 1304 bonded to a series of webs 1306 that connect the
outer ring 418 to housing 450. Deflection of the webs and the
resulting strain of the strain gauge elements will provide a
measurement signal proportional to the output torque of output
shaft 404 of the mechanical option module 104 or to the input
torque to the rotary or linear actuator 106.
As power is transferred from input shaft 402 (from a prime mover)
to output shaft 404 (and out to an actuator), the force or torque
applied to the output shaft 404 is measured by torque sensor 1302.
In some embodiments the torque can be measured very accurately,
such as having an error of less than 1%. In some embodiments the
outer ring 418 mounted on bearings 420 and 422 isolates the torque
sensor 1302 from radial forces or bending loads that may be
generated. As a result, the true torque applied to the rotary or
linear actuator 106 can be precisely measured.
Some of the embodiments of the mechanical option module 104
described herein take advantage of the unique characteristics of a
bearing-mounted planetary gear reducer. When a planetary gear
reducer is configured such that the ring gear is fixed to the
unit's case, the ring gear is non-rotatable. However if the ring
gear is allowed to rotate in the same manner that the sun and
planet gears rotate, then the rotational output of the mechanical
option module 104 can be controlled by, for example, two rather
than one input function. Specifically the output function is the
sum of the two input functions factored by the respective reduction
of each input. Thus by controlling the rotation of the ring gear,
or alternating the sun gear input, the mechanical transfer function
of this device can be readily modified.
Some embodiments of the actuation system described herein provide a
series of different mechanical option models each exhibiting a
unique mechanical transfer function needed to accomplish specific
common applications. In some embodiments, the rotatable ring gear
feature is used to accomplish the intended purpose.
The foregoing discussion illustrates some of the various possible
embodiments. Further, in some embodiments, an actuator and
subassembly are pre-engineered and can be readily connected to each
other to quickly meet the needs of a particular application by
selecting and matching the correct predesigned and possibly
pre-manufactured subassemblies. In another possible embodiment, the
actuator and subassembly are manufactured as a single machine and
not configured to be connected with other actuators or
subassemblies.
In some embodiments several mechanical option modules are
pre-designed and possibly pre-manufactured, each being configured
to perform a different function with an actuators housing when
matched with the actuator, thus allowing unique and specific
control of the actuator's output.
A block diagram illustrating a second exemplary configuration of a
mechanical option module 104 will now be described with reference
to FIG. 14. Several more detailed examples of the mechanical option
module 104 shown in FIG. 14 are then illustrated and described with
reference to FIGS. 15-16.
FIG. 14 is a schematic block diagram and cross-sectional view of
another example mechanical option module 104. In some embodiments,
mechanical option module 104 includes input shaft 1402, output
shaft 1404, planetary gear module 1406, bearing assembly 1408,
application-specific module 1410, and housing 1450. Some components
of this example of mechanical option modules 104 are the same or
similar to the commonly named components discussed in more detail
herein. Accordingly, those components will not be discussed again
in detail below. For example, input shaft 1402, output shaft 1404,
planetary gear module 1406, application-specific module 1410, and
housing 1450, are all similar to input shaft 402, output shaft 404,
planetary gear module 1406, application-specific module 410, and
housing 450 introduced and discussed in more detail herein with
reference to FIGS. 4 and 5.
Input shaft 1402 receives power, such as from prime mover 102. The
power is transferred through input shaft 1402 to sun gear 1412
configured at an end of input shaft 1402. The power delivered to
input shaft 1402 causes input shaft 1402 and sun gear 1412 to
rotate about a longitudinal axis. Sun gear 1412 includes teeth that
extend therefrom, which are configured to engage with teeth of
planetary gears 1414.
A plurality of planet gears are arranged around sun gear 1412,
which also include teeth to engage with the teeth of sun gear 1412.
In this example, planetary gear module 1406 includes three planet
gears 1414, but other embodiments include different quantities of
planet gears 1414. Planet gears 1414 are rotatably connected to
planet carrier 1416. In this example, planet carrier 1416 is
located on both sides of planet gears 1414 (as shown in FIG. 14).
In some embodiments planet gears 1414 include axles 1452 that are
aligned with the axis of rotation of planet gears 1414. When sun
gear 1412 rotates, the rotation is transferred to planet gears
1414, which rotate about their axes of rotation. In some
embodiments axle 1452 also rotate relative to planet carrier 1416,
while in other embodiments planet gears 1414 rotate around axle
1452.
Planetary gear module 1406 also includes outer ring 1418. In some
embodiments, outer ring 1418 includes an inner surface 1432 and an
outer surface 1434. Inner surface 1432 is typically a cylindrical
bore and includes a plurality of teeth configured to engage with
teeth of planet gears 1414. In some embodiments outer surface 1434
includes a smooth outer surface, while in other embodiments, outer
surface 1434 includes a plurality of teeth. In some embodiments the
shape and configuration of outer surface 1434 is determined by the
application-specific module. For example, in some embodiments
illustrated herein the application-specific module requires another
gear coupled to outer ring 1418 which extends from or integral with
outer surface 1434.
Bearing assembly 1408 is provided to separate certain moving
components from each other. In this example, bearing assembly 1408
includes bearing 1460, bearings 1462, and bearings 1464. Multiple
bearings can be substituted for a single bearing and a single
bearing can be substituted for multiple bearings in various
possible embodiments. In addition, in some embodiments one or more
of the bearing are not included (or replaced with an air or liquid
gap), such as when the associated components are adequately
supported by other parts of the mechanical option module or are
externally supported (e.g., input and output shafts).
In this example, bearings 1460 are arranged at an interface between
housing 1450 and input shaft 1402. Bearing 1460 is, for example, a
ball bearing, that permits input shaft 1402 to rotate independent
of housing 1450 and supports input shaft 1402. Bearings 1462 are
arranged at an interface between planet carrier 1416 and outer ring
1418. Bearing 1460 is, for example, a needle bearing, that permits
planet carrier 1416 to rotate independent of outer ring 1434.
Bearings 1464 are arranged at an interface between output shaft
1404 and housing 1450. Bearings 1464 are, for example, ball
bearings, that permit output shaft 1404 to rotate independent of
housing 1450 and supports output shaft 1404.
In this example, there is no mechanical coupling between the
housing 1450 and internal components of the mechanical option
module (e.g., input shaft 1402, output shaft 1404, and planetary
gear module 1406), except as provided by the application-specific
module.
When a torque is provided to input shaft 1402, the torque is
transferred to sun gear 1412, and then to planet gears 1414. Planet
gears 1414 then transfer the torque to outer ring 1418. If outer
ring 1418 is fixed by the application-specific module 1410 with
respect to the housing 1450, all of the torque supplied by planet
gears 1414 to outer ring 1418 is transferred into planet carrier
1416 that supports the planet gears 1414. The torque on the planet
carrier 1416 is then transferred to output shaft 1404, which is
coupled to planet carrier 1416.
As discussed in detail herein, additional functions are provided by
allowing outer ring 1418 freedom to move with respect to the
housing. It is recognized that the examples previously described
herein (e.g., FIGS. 6-12) with reference to the mechanical option
module shown in FIG. 4 form yet other embodiments when combined
with the example mechanical option module shown in FIG. 14. Several
specific examples will now be described to illustrate this in more
detail.
FIG. 15 is a schematic cross-sectional view of another example
mechanical option module 104. The example illustrated in FIG. 15 is
similar in many respects to the example illustrated and described
herein with reference to FIG. 8. More specifically, both
embodiments include an application-specific module 410/1410 that
permits the mechanical option module 104 to interface with a second
drive unit, such as a secondary motor. The example shown in FIG.
15, however, includes the mechanical option module arrangement of
FIG. 14, rather than that of FIG. 4. Various other differences are
also included, as discussed below.
In this example, mechanical option module 104 includes input shaft
1402, output shaft 1404, planetary gear module 1406, bearing
assembly 1408, application-specific module 1410, and housing 1450.
As previously discussed, planetary gear module 1406 includes sun
gear 1412, planet gears 1414, planet carrier 1416, and outer ring
1418, and bearing assembly 1408 includes bearings 1460, 1462, and
1464.
In this example, application-specific module 1410 includes
protruding gear section 1500, secondary input shaft 1502, planetary
gear module 1506 (including sun gear 1512, planet gears 1514,
planet carrier 1516, and outer ring 1518), bearing assembly 1508
(including bearings 1560, 1562), and protruding gear section
1510.
In some embodiments, application-specific module 1410 is configured
to be coupled to a secondary drive unit (e.g., a motor) through
input shaft 1502. When in operation, the secondary drive unit
provides a torque to input shaft 1502 causing it to rotate. Some
embodiments include a secondary drive unit with a brake that
prevents (or reduces) rotation of input shaft 1502 when the
secondary drive unit is not in operation. Alternatively, in some
embodiments a separate brake mechanism is provided, such as to
engage protruding gear section 1510.
During operation of the secondary drive unit, a torque is supplied
by the drive unit to input shaft 1502. The torque is transferred to
sun gear 1512, into planet gears 1514, and into outer ring 1518 and
protruding gear section 1510. In some embodiments planet carrier
1516 is rigidly connected to housing 1450 to prevent rotation of
planet carrier 1516. Protruding gear section 1510 is engaged with
protruding gear section 1500, and therefore transfers the torque
into protruding gear section 1500. Upon rotation of protruding gear
section 1500, outer ring 1418 (from which protruding gear section
1500 extends) is also caused to rotate. The rotation is then
transferred through planet gears 1414 and planet carrier 1416, such
as to increase the speed of rotation of the output shaft 1404.
In some embodiments the two drive units are substantially similar.
In another embodiment, the two drive units are different, such as
one being a high torque and low speed drive unit, and the other
being a low torque and high speed drive unit. In another possible
embodiment, input shaft 1502 is a manual input shaft configured to
receive a manual input, such as from a wrench, hand tool, or hand
power tool (e.g., a drill).
In some embodiments, the mechanical option module 104 illustrated
in FIG. 14 is operated as a redundant system, where the secondary
drive unit is provided in case of failure of the first drive unit.
For example, when the controller 108 (shown in FIG. 1) detects a
failure of the prime mover 102, controller 108 activates the
secondary drive unit.
The example shown in FIG. 15 allows for two separate inputs into
the mechanical option module, including an input on input shafts
1402 and 1502. In yet another possible embodiment, a third input is
provided. To provide an additional input, for example, an input
shaft is provided through housing 1450 and connects to planet
carrier 1516 (in a similar manner as output shaft 1404 and planet
carrier 1416 directly below). In this example, the planet carrier
1516 is not rigidly connected to housing 1450, and can include
bearings (similar to bearings 1464) separating the input shaft from
the housing. The third input can be used for a variety of reasons,
such as redundancy or to adjust the speed of the output shaft
1404.
FIG. 16 is a schematic cross-sectional view of another example
mechanical option module 104. The example illustrated in FIG. 16 is
similar in many respects to the example illustrated and described
herein with reference to FIG. 12. More specifically, both
embodiments include an application-specific module 410/1410 that
permits the mechanical option module 104 to store and selectively
deliver energy. The example shown in FIG. 16, however, includes the
mechanical option module arrangement of FIG. 14, rather than that
of FIG. 4. Various other differences are also included, as
discussed below.
In this example, mechanical option module 104 includes input shaft
1402, output shaft 1404, planetary gear module 1406, bearing
assembly 1408, application-specific module 1410, and housing 1450.
As previously discussed, planetary gear module 1406 includes sun
gear 1412, planet gears 1414, planet carrier 1416, and outer ring
1418, and bearing assembly 1408 includes bearings 1460, 1462, and
1464.
In this example, application-specific module 1410 includes
protruding gear region 1600, gear 1602, lead screw 1604, spring
1606, nut 1608, and brake 1610. Gear 1602 includes teeth that
engage with teeth of protruding gear region 1600. Gear 1602 is
connected to lead screw 1604, such that when gear 1602 rotates the
lead screw 1604 also rotates. In some embodiments lead screw 1604
includes a helix angle suitable to allow the screw to backdrive.
Lead screw 1604 extends into spring return region 1620, through
second end 1624, and to first end 1622.
Spring 1606 is contained within spring return region 1620. In this
example, spring 1606 is a helical compression spring. Lead screw
1604 extends approximately along a central axis of spring 1606. One
end of spring 1606 is connected to or presses against first end
1622 of spring return region 1620. The other end of spring 1606 is
connected to or presses against nut 1608.
Nut 1608 is a threaded nut that rides on screw 1604 in the region
between first and second ends 1622 and 1624 of spring return region
1620. Nut 1608 includes a threaded inner surface that causes nut
1608 to translate between first and second ends 1622 and 1624 as
lead screw 1604 rotates. In some embodiments, nut 1608 includes an
anti-rotation mechanism, such as protruding arms that ride within
tracks (not shown) formed in sidewalls of spring return region
1620. In some embodiments, the arms are keyed features that ride in
a keyway. In another embodiment, the shape of nut 1608 (e.g.
squared, etc.) matches the internal shape of spring return region
1620.
Brake 1610 is provided to selectively engage lead screw 1604 in
this embodiment. In other possible embodiments, brake 1610 operates
to selectively engage with one or more of: gear 1602, protruding
gear region 1600, outer ring 1418, or similar components to prevent
rotation of lead screw 1604 when engaged.
Brake 1610 is selectively disengaged to allow rotation of lead
screw 1604. After energy has been stored in the compressed spring
1606, disengagement of brake 1610 causes energy to be transferred
from spring 1606 into nut 1608, which causes rotation of lead screw
1604. The resulting torque is then transferred into gear 1602 and
into the protruding gear region 1600, causing rotation of outer
ring 1418.
Several example applications of the mechanical option module shown
in FIG. 16 are the same or similar to those discussed herein with
reference to FIG. 12.
The various embodiments described above are provided by way of
illustration only and should not be construed to limit the claims
attached hereto. Those skilled in the art will readily recognize
various modifications and changes that may be made without
following the example embodiments and applications illustrated and
described herein, and without departing from the true spirit and
scope of the following claims.
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